Electrical energy-generating heat sink system and method of using same to recharge an energy storage device

ABSTRACT

An electrical energy-generating heat sink system is described herein that provides a convenient and economical method for continuously recharging an energy storage device in electronic devices.

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/991,110, filed Nov. 16, 2001, which is incorporated hereinby reference.

CROSS REFERENCES

[0002] This application is related to the following U.S. patentapplications which are assigned to the same Assignee as the presentapplication:

[0003] U.S. patent application Ser. No. 09/583,802, filed on May 31,2000, entitled “Integrated Circuit Refrigeration Device;” and

[0004] U.S. patent application Ser. No. 09/746,554, filed on Dec. 22,2000, entitled “An Integrated Vapor Chamber Heat Sink and Spreader andan Embedded Direct Heat Pipe Attachment.”

TECHNICAL FIELD

[0005] This invention relates generally to heat sink systems, and inparticular, the present invention relates to an electricalenergy-generating heat sink system.

BACKGROUND

[0006] Electronic devices in use today are requiring ever-increasingamounts of power. Portable energy sources in such devices provide onlylimited use until the unit is recharged or the energy source isreplaced. Typically, recharging can only be performed when the device isnot being used (e.g., by placing the energy source or the entire devicein a recharging unit) or otherwise requires a hook-up to the power gridor other external energy source, e.g., automobile cigarette lighter.

[0007] In the mobile computing environment, one of the primarychallenges has been to extend battery life to enable consumers toprolong the use of the device while mobile. In the past, this challengehas typically been met by building low power processors where powerconsumption is minimized through circuit design and/or power throttlingfeatures. However, persistent consumer demand for higher performancerenders this approach impractical. For example, recently developedmobile applications use processors requiring 30 watts or more of powerto be drawn off over a temperature of about 100° C. Other efforts havefocused on extending battery life, although results, to date, have beenincremental at best.

[0008] For the reasons stated above, there is a need in the art for asimple, yet effective means for extending the life of portable energysources.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a block diagram describing an electricalenergy-generating heat sink system in one embodiment of the presentinvention.

[0010]FIG. 2 is a simplified schematic of one embodiment of theelectrical energy-generating heat sink system of FIG. 1.

[0011]FIG. 3 is a perspective view of a portion of an exemplary turbinein the electrical energy-generating heat sink system of FIG. 2.

[0012]FIG. 4 is a simplified cross-sectional view of an exemplaryturbine array in the electrical energy-generating heat sink system ofFIG. 2.

[0013]FIG. 5 is an illustration of another embodiment of the electricalenergy-generating heat sink system of FIG. 1 in one embodiment of thepresent invention.

[0014]FIG. 6 is a simplified perspective view of the vapor chamber baseof FIG. 5 in one embodiment of the present invention.

[0015]FIG. 7 is a block diagram of a method for providing electricalenergy to a rechargeable energy storage device with the system of FIG. 1in one embodiment of the present invention.

[0016]FIG. 8 is a block diagram of a method for extending run-time for abattery-operated notebook computer.

DETAILED DESCRIPTION

[0017] In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the inventions may bepracticed. In the drawings, like numerals describe substantially similarcomponents throughout the several views. These embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,electrical, and other changes may be made without departing from thespirit and scope of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined only by the appended claims,along with the full scope of equivalents to which such claims areentitled.

[0018] Definitions

[0019] As used herein, the term “working fluid” refers to a multi-phaseliquid that can change between a liquid and a vapor at the operatingtemperatures and pressures of the system it is being used in.

[0020] As used herein, the term “heat pipe” refers to a heat transferdevice. Heat pipes transfer heat by the evaporation and condensation ofa working fluid. A heat pipe is a vacuum tight vessel which is evacuatedand partially back-filled with the working fluid. As heat is input tothe heat pipe, the fluid is vaporized, creating a pressure gradientwithin the heat pipe, which forces the vapor to flow. This heatedportion is often referred to as the “evaporator portion.” In aconventional heat pipe, this flow consists of all the vaporized fluidmoving towards the cooler portion of the pipe, i.e., the condenserportion, where it condenses, giving up its latent heat of vaporization.The working fluid is then returned to the evaporator portion. In mostinstances, this is accomplished with some type of “pump,” such as with amechanical condenser, capillary forces developed in a wick structure,and so forth. Such a pump is needed as a heat pipe is considered by manyto include only devices oriented to work against gravity. (Common usageof the term “heat pipe,” however, sometimes includes reference todevices that have no wick structure, such as thermosyphons definedbelow). A heat pipe can be bent and formed into any number ofconfigurations and is considered to include any type of “vapor spreader”such as a “vapor chamber.”

[0021] As used herein, the term “vapor chamber heat sink” refers to avapor chamber in combination with cooling fins, rods and so forth. Thevapor chamber base portion of a typical vapor chamber heat sinktypically consists of an evaporator, an adiabatic section and acondenser. It is the evaporator or evaporator portion that is placed incontact with the heat-generating device. The vapor chamber in a vaporchamber heat sink may further include a type of pumping means, such as awick, to provide a return path from the condenser to the evaporator.

[0022] As used herein, the term “thermosyphon” refers to a heat transferdevice that is gravity aided, having no additional pumping means. Athermosyphon, therefore, technically includes a vapor chamber having nowick structure, although such a chamber is often referred to as a typeof heat pipe. Such a vapor chamber is necessarily oriented with thecondenser portion located above the evaporator portion.

[0023] As used herein, the term “thermal solution” refers to a heattransfer device commonly used to cool a central processing unit (CPU).The term “thermal solution” is sometimes used interchangeably with theterm “heat sink,” which can include a fan (sometimes referred to as a“fansink”).

[0024] As used herein, the term “battery” refers to an electrochemicalenergy storage device or direct-current voltage source that convertschemical, thermal, nuclear or solar energy into electric energy. Abattery stores electrical energy using electrochemical cells. Chemicalreactions occur spontaneously at the electrodes when connected throughan external circuit, producing an electrical current. The physicalconstruction of a battery is such that it does not permit theintermixing and consequent direct reaction of the chemicals stored init. Although a battery typically consists of several cells coupled inseries or parallel, or any combination thereof, a single cell iscommonly referred to as a battery.

[0025] As used herein, a “rechargeable battery” refers to a battery inwhich the chemical reaction system providing the electrical current ischemically reversible. After discharging, a rechargeable battery can berecharged by applying an electrical current to its terminals. Arechargeable battery is also referred to as a secondary battery,accumulator battery, storage battery, and so forth. Rechargeablebatteries typically used in portable computing devices, such as notebookcomputers include nickel cadmium, nickel metal hydride and lithium ionbatteries.

[0026] As used herein, the term “battery charger” refers to a devicethat provides electrical energy to a rechargeable battery, causing it torecharge. Again, common usage often refers to a battery charger asapplying “power” to charge a battery, although this technically refersto the “rate” at which the electrical energy can be supplied. Usuallythe voltage and current are controlled so the battery is chargedrapidly, but without undue stress.

[0027] As used herein, the term “charging” refers to a process for“filling” a rechargeable battery with electricity by applying a currentto its terminals. The process will cause electrochemical reactions tooccur in the battery, storing the electricity in chemical form. (Incontrast, during the charging of a capacitor the electricity is storedas electrical charges, without causing any chemical reactions to occur).

[0028] As used herein, the term “electrical source” refers to a type ofenergy source, i.e., a source of electrical current. It can beelectrochemical (battery or fuel cell) or an electromechanical device(dynamo) or a specialized electronic instrument. Specialized sources canbe called a “voltage source” or a “current source,” indicating thecharacteristic of the electrical power that can be controlled by thatdevice.

[0029] As used herein, the term “electrical energy” refers to theability of an electrical source to carry out useful work or generateheat. For example, this energy can be used to drive an electrical motorand carry out mechanical work, or to generate heat with an electricalheater. Electrical energy is usually expressed in units of watt-hour(Wh).

[0030] As used herein, the term “electrical power” refers to the rate atwhich an electrical source can supply electrical energy. For example, abattery may be able to store a large amount of energy, but if it has asmall power capability it can provide the energy (do some work) onlyslowly, and it will take a long time to discharge. Another battery withthe same energy storage capability but larger power will provide theenergy (do work) faster, but will also be discharged faster. Electricalpower is expressed usually in units of watt (W). The terms “power” and“energy” are often used interchangeably, e.g., “energy source” is oftenequated with “power source” and such usage may occur herein, although itis to be appreciated that the context in which the term is used providesany necessary clarification. “Loads” are also characterized by a powerrating, e.g., an electrical motor or a light bulb is characterized bythe power needed to operate it.

[0031] As used herein, the term “energy efficiency” refers to afraction, usually expressed as a percentage of electrical energy storedin a rechargeable battery that is recoverable during discharging. Thepercentage is dependent on several factors, including currentefficiency, heat losses, and so forth.

[0032] As used herein, the term “turbine generator” refers to anelectric generator that is driven by steam, gas, or hydraulic turbinecoupled to it for electric power production. The term “generator” asused herein refers to a machine by which mechanical energy is changedinto electrical energy through use of magnetic fields. If the electricalenergy output by the generator is DC, the generator is referred to as a“DC generator.” If the electrical energy that is output is analternating current, the generator is referred to as an “alternator.”All generators have a stationary stator and a rotating rotor. Therotating rotor is mounting on bearings so it can rotate, with a rotorshaft sticking out beyond the generator housing. Input to a generator isprovided by a “prime mover” which, in this instance, is a “turbine”coupled to the rotor shaft of the generator in order to provide therequisite torque. The term “turbine” as used herein refers to a rotaryengine actuated by the reaction or impulse or both of a current of fluidor vaporized fluid subject to pressure. A turbine is typically made witha series of vanes or blades on a central rotating spindle.

[0033] As used herein, the term “MEMS” refers to Micro-ElectricalMechanical Systems. MEMS are electrical machines built on silicone usinglithography processes and standard silicon manufacturing processes.Examples include MEMS-based turbine engines, turbine-generators,condensers, compressors, and so forth.

[0034] Description of the Embodiments

[0035] An electrical energy-generating heat sink system is describedherein that provides a convenient and economical method for continuouslyrecharging an energy storage device in electronic devices. In oneembodiment, the system includes a refrigeration system in combinationwith an electricity generating device. Working fluid in therefrigeration system is vaporized in a heat transfer device and thenchanneled through a vapor pressurizing device, such as a compressor, toproduce pressurized vapor. The pressurized vapor then passes through theelectricity generating device, such as a turbine generator, whichprovides electrical energy to the rechargeable energy storage device,such as a notebook battery. Excess vapor is reliquified in the heattransfer device for use again in the system.

[0036]FIG. 1 shows a simplified block diagram of an electricalenergy-generating system 100. In one embodiment, the electricalenergy-generating system 100 includes a heat transfer device 102, acompressor 104 and a turbine generator 106. A working fluid present inthe heat transfer device 102 is converted to vapor by a heat source 110,such as a microprocessor. The vapor is then directed from the heattransfer device 102 to the compressor 104 where it is pressurized priorto its release into the turbine generator 106. The pressurized vaporcauses the blades in the turbine portion of the turbine generator 106 torotate, producing mechanical energy. This mechanical energy is convertedto electrical energy in the generator portion of the turbine generator106, which is provided to a rechargeable energy source 112, such as abattery. Excess vapor from the turbine generator 106 re-enters the heattransfer device 102, where it is reliquified by cooling for use again inthe electrical energy-generating system 100.

[0037] Each component of the electrical energy-generating system 100 canbe any suitable size and shape, as long as the system fits togetherproperly to perform the intended function. In one embodiment, theelectrical energy-generating system is designed to accommodate a rangeof sizes and types of electronic devices. In yet another embodiment, theelectrical energy-generating system is custom designed for any type ofunique application. In an exemplary embodiment, the electricalenergy-generating system 100 can be used in a laptop computer and isbetween about five (5) and ten (10) mm thick.

[0038] Heat transfer device designs vary, and the present invention isnot limited to any specific design, although space constraints incertain environments, such as the mobile environments, certainlyinfluence the final design. In one embodiment, the heat transfer devicecomprises a straight hollow tube partially filled with a liquid with theair evacuated from the unfilled volume. The liquid and its vapor withinthe tube are in equilibrium at the partial pressure of the liquid. Themain thermal transfer mechanism with this type of device is the storageand release of the latent heat of vaporization of the liquid. One end ofthe tube serves as an evaporator while the other end acts as acondenser. Heat applied to the evaporator boils the liquid, convertingit to its vapor phase. The heat transferred is the latent heat of liquidvaporization. The vapor enters the condenser, where it condenses byreleasing the latent heat of vaporization. The condensed liquid thenreturns to the evaporator where it is reliquified prior to transfer tothe liquid reservoir for use again in the system. In most embodiments,the system operates at less than one (1) atmosphere of pressure. In suchembodiments, it is important for air not to leak into the heat transferdevice. Otherwise, the fluid would slowly vaporize as it reaches itsatmospheric boiling point.

[0039] This type of heat transfer device does not have a set thermalconductivity due to the use of two-phase heat transfer. However, it isgenerally known that the effective thermal conductivity improves with anincrease in certain dimensions. Unlike solid materials, the effectivethermal conductivity in heat pipes and thermosyphons changes with theamount of energy being transferred as well as with the size of theevaporator and condenser portions of the heat transfer device.

[0040] Various types of commercial heat transfer devices are available,such as the heat pipes made by Thermacore,® Inc. in Lancaster, Pa. Theheat transfer device 102 can further include separate condenser andevaporator sections that are thermally and/or fluidly coupled to eachother via a pumping device, such as a wick. See, for example, U.S.patent application Ser. No. 09/583,802, filed on May 31, 2000, entitled“Integrated Circuit Refrigeration Device” (hereinafter “U.S. applicationSer. No. 09/583,802”).

[0041] The present invention operates by diverting the normal flow ofvapor in a heat transfer device to a vapor pressurizing device and theninto electricity producing components in order to produce electricalenergy as described herein. Consequently, if commercial heat transferdevices are used, such as the Thermacore® heat pipes noted above,suitable modifications would need to be made.

[0042] In one embodiment, the heat transfer device 102 is athermosyphon. In another embodiment, the heat transfer device 102 is aheat pipe. In a particular embodiment, the heat transfer device 102 is avacuum chamber heat sink that can serve as a heat pipe or athermosyphon. In such a device, the heat dissipating region typicallyincludes heat dissipation elements such as fins or rods that providelarge surface areas for spreading heat. The heat transfer device can bemade from any suitable material. In one embodiment, the heat transferdevice is made from copper or a copper-based material. The heat transferdevice 102 can further include a fan, as is known in the art, whichprovides air movement to increase the amount of heat dissipated overtime. The heat transfer device and/or each portion thereof is thermallyand/or fluidly coupled to other components in the system.

[0043] It is appreciated that virtually any mechanism can be used tocool the excess vapor exiting the turbine blades. In one embodiment, aconventional condenser arrangement, as described herein, is used toreliquify the vapor. In another embodiment, a separate energy source,such as the type of energy provided by a thermoelectric cooler, is used.(A thermoelectric cooler is capable of providing heating or cooling,depending on the polarity of its voltage.)

[0044] Any suitable type of fluid known in the art can be used. Thisincludes, but is not limited to methanol, ammonia and acetone. Althoughwater, e.g., deionized water, also has excellent thermal properties andis known to adequately cool heat sinks, it may be less efficient withregard to its ability to provide highly-pressurized forces to theturbine blades due to its relatively low vapor pressure, i.e., less thanone (1) atm at operating temperature. In another embodiment, low-boilingpoint dielectric fluids are used, i.e., fluids that boil at less thanabout 40° C. Examples include, but are not limited to, hydrofluoroethers(HFE), chlorofluorocarbons (CFC), and so forth. Although low-boilingfluids may not provide as much cooling for the heat sink as fluidshaving a relatively low vapor pressure, the higher vapor pressure fromsuch fluids, i.e., in excess of about three (3) atm at operatingtemperature, allows the turbines to operate more efficiently.Specifically, since the turbine blades spin faster with the increasedpressure or force, more electrical energy is produced per given volumeof fluid. In yet another embodiment, high-boiling dielectrics are used.The optimum fluid will ultimately depend on a specific application. Inother embodiments, liquid metals such as sodium and potassium are used.Generally, the amount of fluid used herein is quite small, e.g., lessthan one (1) mL to about ten (10) mL.

[0045] Other components in the system, such as the compressor 104 andturbine generator 106 can also take any form. In one embodiment, anysuitable type of device is used that is capable of performing theintended function. In another embodiment one or more of the componentsare MEMS devices, as defined herein. Each of the components are coupledin any suitable manner. In one embodiment, the components are fluidlyand/or thermally and/or electrically and/or mechanically coupled, asthose terms are understood in the art. In another embodiment, theturbine generator is replaced by two separate components, namely aturbine and a generator coupled together in any suitable manner.

[0046] In one embodiment, the compressor is a turbine compressor, screwcompressor or centrifugal compressor, although the invention is not solimited. In another embodiment, the compressor is an acoustic compressoras described in U.S. Pat. No. 5,319,938, issued Jun. 14, 1994 to TimothyLucas and in U.S. application Ser. No. 09/583,802, supra. It isappreciated that the compressor can be driven by any suitable means,such as with a piezoelectric device.

[0047] In one embodiment, the turbine or turbine portion of a turbinegenerator has high speed rotating blades, such as a micro radial inflowturbine. In another embodiment, the generator or generator portion of aturbine generator is a micro electrostatic starter generator.

[0048] It is understood that components integral to these devices, suchas bearings, and so forth, need to be compatible with the micro deviceenvironment. In one embodiment, the bearings are electromagnetic, air,journal (e.g., cylindrical rotor, wave, foil, etc.), electric and soforth. Other design considerations include maintaining suitable Reynoldsnumbers, air pressure, shaft speed and so forth. Furthermore, thematerials, including the electrical infrastructure used to conductelectricity from the turbine generator to the rechargeable energystorage device, will not be discussed in detail herein. Such designconsiderations are known to those skilled in the art.

[0049] For a discussion of MEMS technology, see, for example, A. H.Epstein, et al., Shirtbutton-Sized Gas Turbines: The EngineeringChallenges of Micro High Speed Rotating Machinery, presented at the 8thInt'l Symposium on Transport Phenomena (hereinafter “Epstein”) andDynamics of Rotating Machinery (ISROMAC-8), Honolulu, HI., March 2000and A. H. Epstein, Micro Turbine Engines for Soldier Power, presented at“The Defense Science and Technology Seminar: Future Warrior Systems,”October 2000.

[0050]FIG. 2 shows a simplified schematic of one embodiment of thepresent invention. The electrical energy-generating system 200 in thisembodiment includes a vapor chamber heat sink 202, a MEMS compressor204, a MEMS turbine 206 and a MEMS generator 208. The vapor chamber heatsink 202 comprises a hollow vapor chamber base 210 and a plurality offins or rods 212. The hollow vapor chamber base 210 includes a fluid 214under pressure within a chamber 216. The vapor chamber heat sink 202 isused to conduct heat 213 away from a heat generating device, such as theintegrated circuit package 218 shown mounted to a substrate 220 in FIG.2.

[0051] It will be appreciated that the integrated circuit package 218can contain any type of integrated circuit that produces heat. However,the present invention is particularly suited for processors used in themobile environment that operate at high speeds and produce relativelylarge amounts of heat, such as about 30 watts or more over a temperatureof about 100° C. The substrate 220 is any kind of carrier, such as acircuit board, a motherboard or a test board. In this embodiment, alayer of thermal interface material 222 is interposed between theintegrated circuit 218 and the vapor chamber heat sink 202. Thethickness of the layer of thermal interface material 222 is highlyexaggerated for clarification. A thermal interface material is usually athin layer of material that produces intimate, poreless thermal contact,e.g., typically less than about 0.1 mm in thickness.

[0052] In one embodiment, the vapor chamber heat sink embodiments shownherein are comparable to the heat sinks described in U.S. patentapplication Ser. No. 09/746,554, filed on Dec. 22, 2000, entitled “AnIntegrated Vapor Chamber Heat Sink and Spreader and an Embedded DirectHeat Pipe Attachment,” although there is not necessarily a wickstructure in the present invention. In another embodiment, the vaporchamber heat sinks are comparable to the heat sinks described in “U.S.application Ser. No. 09/583,802,” supra.

[0053] As shown in FIG. 2, the fluid 214 exits the heat sink 202 as avapor 224. After passing through the compressor 204 the vapor emerges aspressurized vapor 226 that is propelled through the turbine 206 (or aturbine-portion of a turbine generator), producing mechanical energy 228that is converted to electrical energy 230 in the generator 208. Theelectrical energy 230 then passes through appropriate electricalinfrastructure to provide electricity to a rechargeable battery 232.Excess vapor 234 also exits the turbine 206 and is returned to the heatsink 202 where the process begins again.

[0054]FIG. 3 shows one embodiment of a fan blade arrangement in aturbine 306. In this type of turbine, typically referred to as a microradial inflow turbine, the shape, size, orientation, etc., of the innerrow of rotor blades 312 and the outer row of stator blades 314 aredesigned according to the particular application. Considerations ondesign include airfoil height, centrifugal bending stress at the bladeroot, adequate support for radial loads, and so forth.

[0055]FIG. 4 is a simplified illustration of one embodiment of a seriesof turbine plates 402, each containing five turbines 206, although theinvention is not so limited. Any number of turbines 206 can be used asdesired for a particular application in order to maximize the generationof electricity. The turbines 206 can be arranged in any manner, e.g., inseries or parallel, although greater efficiency may be achieved by usinga combination of both serial and parallel. In the embodiment shown inFIG. 4, the turbines 206 are arranged in parallel on each individualplate 402, with four plates 402 arranged in series with the connectionexiting the compressor, although any number of turbine plates 402 can beused as desired. If the turbines are arranged only in parallel, this cancause each turbine to operate at a proportionately lower pressure,because the entering pressurized vapor is now split into multiple flowpaths. The lower pressure reduces the rate at which the turbine bladesspin, thus reducing energy production. Similarly, arranging the turbinesin series may also reduce energy production, i.e., each time the vaporpasses through a turbine, some “energy” is lost and less work can bedone when it passes through the next turbine. The actual design thatprovides the greatest efficiency can be determined through testing ofvarious combinations, types and numbers of turbines, given the spaceconstraints of a given electronic device.

[0056]FIG. 5 is a simplified schematic view of an alternative vaporchamber heat sink 502. In this embodiment the vapor chamber heat sink502 comprises a vapor chamber base 510 and a plurality of fins or rods512. In the embodiment shown, a fan 515 located above the heat sink 502assists in removing heat 513, although the invention is not so limited.The hollow vapor chamber base 510 includes a fluid under pressure withina substantially triangular chamber 516. The fluid passes through acompressor 504 and an array of turbine-generators 507 located within thechamber 516. The electrical energy produced is directed to therechargeable energy storage device. One-way valves 540 and 550 ensurethat the flow of fluid is as desired within the chamber 516.

[0057] The triangular-shaped chamber 516 shown in FIG. 5 has theadvantage of using gravity to return the fluid back to the lower portionof the chamber. In another embodiment, any suitable geometry can be usedthat provides the requisite incline. In yet another embodiment, thechamber 516 is oriented in any direction and fluid movement is providedand/or assisted by other pumping means, such as with a wick.

[0058]FIG. 6 is a simplified perspective view of the vapor chamber base510 of FIG. 5. As can be seen, multiple chambers 516 can be used toincrease the efficiency and output of the electrical energy-generatingsystem. The chambers 516 in FIG. 6 alternate in orientation, althoughthe invention is not so limited. Such an arrangement, however, is likelyto reduce or eliminate hot spots within the heat sink, as the heat isbeing directed in alternating directions.

[0059]FIG. 7 is a block diagram describing a method for recharging anenergy storage device in one embodiment of the present invention. In theinitial step heat is generated 702 by a heat generating device. The heatvaporizes 704 a working fluid in thermal contact with the heatgenerating device. This vapor is then pressurized 706 by a vaporpressurizing device and forced through turbine blades to produce 708mechanical energy. A generator (or alternator) converts 710 themechanical energy to electrical energy, which is then routed 712 to therechargeable energy storage device. Excess vapor from the turbine bladesin step 708 is reliquified 714 for use again as a working fluid.

[0060] The electrical energy-generating system of the present inventioncan be designed to efficiently and economically extend the usage of anytype of device that generates heat and requires an energy source. Thisincludes, but is not limited to mobile devices such as computers,digital assistants, cell phones, global positioning system receivers,robots, electrical vehicles, cell phones and so forth. However, deviceswhich are run only intermittently, such as cell phones that are cycledon and off, may not benefit fully from the electrical energy-generatingfeatures of the present invention, as the necessary heat that fuels theprocess would only be generated during the short periods while the unitis being operated. In one embodiment, the electrical energy-generatingsystem, in combination with a suitable battery or battery pack, is usedas a back-up generator for heat-generating devices routinely connectedto the power grid, such as desk-top processors (e.g., in which 50 to 500watts of power is generated over a temperature of about 100° C.),refrigerators, high-speed modems, and so forth. In another embodiment,the electrical energy-generating system, in combination with a suitablebattery system, is utilized as the primary energy source for deviceswhere access to the power grid is impractical and/or not desirable forenvironmental and/or economic reasons, thus providing mobility for usersof devices in remote locations.

[0061] It is estimated that as much as five (5) to six (6) Watt-hours ofelectrical energy can be provided to a rechargeable energy storagedevice, such as a notebook battery, with the electricalenergy-generating system of the present invention, assuming about ten(10) % efficiency. In other embodiments, electrical energy in excess offive (5) to six (6) Watt-hours is provided to the rechargeableelectrical source. In yet other embodiments, the efficiency is greaterthan about ten (10) %.

[0062] With regard to notebook computers, it is known that run timevaries from computer to computer, based on the applications being used(i.e. high graphics, games), the number of times something is saved orretrieved from the hard drive and/or CD Rom drive, the memory ofnotebook, the chemistry and capacity of the battery, and so forth. Arealistic average run-time for a conventional battery is 1.5 to three(3) hours. The ability of the electrical energy-generating heat sink ofthe present invention to serve as a battery charger in a notebookcomputer can likely increase run-time by at least five (5) to ten (10) %or more. In yet other embodiments, run-time may be unlimited, comparableto using a conventional power-grid source.

[0063]FIG. 8 is a block diagram of a method for extending run-time for abattery-operated notebook computer comprising continuously generatingheat 802 with a microprocessor; transferring 804 the heat through a heatsink to continuously produce electrical energy, the heat sink includinga compressor and a turbine generator; continuously providing theelectrical energy to a battery 806 in the notebook computer to rechargethe battery, wherein run-time is extended for the notebook computer.

[0064] Batteries used in portable computing equipment typically lastbetween 12 to 18 months, although the life of a battery is moreaccurately measured in charge/discharge cycles. Nickel metal hydride andlithium iodine batteries typically average about 500+ cycles. It ispossible that the in situ continuous recharging device of the presentinvention may actually extend battery life since the battery isconstantly being recharged during use, experiencing fewer cycles.Appropriate tests under suitable conditions can be performed todetermine the extent of this possible advantage. The energy efficiencyof the rechargeable battery may also be improved with the presentinvention, i.e., the percentage of electrical energy stored in arechargeable battery that is recoverable during discharging. However, asnoted herein, this percentage is dependent on several factors, includingcurrent efficiency, heat losses, and so forth.

[0065] It is also possible that the present invention can be modified toassist with the problem of self-discharging that occurs when a batteryremains for extended periods in an unused electronic device, i.e.,installation of a secondary generator system that functions when theprocessor is not operating to keep the battery fully charged. Currently,if an electronic device having a rechargeable battery, such as anotebook computer, is left plugged into the power grid, the battery mayover-heat, causing the battery cells to slowly deteriorate over time.Use of a MEMS-based generator designed to be operational during non-usecan likely be more closely controlled and limited in order to avoidover-heating of the battery.

[0066] The present invention further reduces or eliminates theoverheating problems inherent with batteries in many electronic devices,particularly portable electronic Overheating can lead to failure ofother components, causing expensive repairs or even replacement of theentire unit. Furthermore, unlike recharging means that require removalof the batteries for placement in a separate charger, the rechargingmeans of the present invention provides convenient and continuousrecharging during use, without the operator needing to take anyadditional steps. By virtually eliminating reliance on the conventionalpower grid, the present invention is energy efficient andenvironmentally-friendly.

[0067] Use of a vapor chamber heat sink has the further advantage ofalleviating the problem of thermal spreading resistance, which canresult in hot spots developing directly over the processor. Vaporchamber heat sinks are generally known to be smaller and lighter thantraditional heat sinks. Additionally, the cooling fins are likely to bemore efficient because they are all at or near the same temperature.

[0068] Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. For example, therefrigeration system described herein might be replaced by asuitably-designed magnetic refrigeration system, thus eliminating theneed for a fluid-based heat pipe. This application is intended to coverany adaptations or variations of the present invention. Therefore, it ismanifestly intended that this invention be limited only by the claimsand the equivalents thereof.

What is claimed is:
 1. An electrical energy-generating systemcomprising: a heat transfer device responsive to heat generated by amicroprocessor; a vapor pressurizing device thermally coupled to theheat transfer device; and an electricity-generating device thermallycoupled to the compressor.
 2. The electrical energy-generating system ofclaim 1 wherein the electricity-generating device is further fluidlycoupled to the heat transfer device.
 3. The electrical energy-generatingsystem of claim 2 wherein the heat transfer device contains a workingfluid.
 4. The electrical energy-generating system of claim 3 wherein theworking fluid is a dielectric.
 5. The electrical energy-generatingsystem of claim 4 wherein the dielectric is a hydrofluoroether orchlorofluorocarbon.
 6. The electrical energy-generating system of claim4 wherein the working fluid is selected from the group consisting ofdeionized water, ammonia, acetone and methanol.
 7. The electricalenergy-generating system of claim 1 wherein the vapor pressurizingdevice is a compressor and the electricity generating device comprises aturbine generator.
 8. The electrical energy-generating system of claim 7wherein the turbine is mechanically coupled to the generator and fluidlycoupled to the compressor.
 9. The electrical energy-generating system ofclaim 8 comprising a plurality of turbines.
 10. The electricalenergy-generating system of claim 9 wherein the plurality of turbinesare arranged in parallel on a turbine plate, further wherein the turbineplate is arranged in series with the compressor.
 11. The electricalenergy generating system of claim 1 wherein the electricity generatingdevice comprises a turbine and an alternator, the alternator capable ofproviding energy to an external AC device.
 12. The electricalenergy-generating system of claim 11 wherein the turbine is mechanicallycoupled to the alternator and fluidly coupled to the compressor.
 13. Theelectrical energy-generating system of claim 2 wherein the heat transferdevice is a heat pipe or thermosyphon.
 14. The electricalenergy-generating system of claim 13 wherein the heat transfer device isa vapor chamber heat sink.
 15. The electrical energy-generating systemof claim 14 wherein the vapor chamber heat sink contains separateevaporator and condenser sections fluidly coupled together.
 16. Theelectrical energy-generating system of claim 14 wherein the vaporchamber heat sink is a heat pipe containing a wick.
 17. The electricalenergy-generating system of claim 14 wherein the vapor chamber heat sinkcomprises a hollow vapor chamber base and a plurality of fins.
 18. Theelectrical energy-generating system of claim 17 further comprising: achamber contained within the hollow vapor chamber base, the chamberadapted to house the electricity-generating device.
 19. The electricalenergy-generating system of claim 18 wherein the electricity generatingdevice is comprised of a compressor and a plurality of turbinegenerators, further wherein the chamber is substantially triangular. 20.The electrical energy-generating system of claim 19 wherein the hollowvapor chamber base houses a plurality of substantially triangularchambers, each sequential chamber oriented in an opposing direction. 21.The electrical energy-generating system of claim 20 wherein electricitygenerated by the electricity generating device is routed to arechargeable energy storage device.
 22. The electrical energy-generatingsystem of claim 21 wherein the rechargeable energy storage device is abattery.
 23. The electrical energy-generating system of claim 1 whereinthe compressor and electricity generating device are micro-electricalmechanical systems (MEMS) devices.
 24. An electrical energy-generatingheat sink system comprising: a vapor chamber heat sink containing aworking fluid; a compressor fluidly coupled to the vapor chamber heatsink; and a MEMS turbine generator thermally coupled to the compressorand configured to provide electrical energy to a rechargeable battery inan electronic device.
 25. The electrical energy-generating heat sinksystem of claim 24 wherein the electronic device is a notebook computer.26. The electrical energy-generating heat sink system of claim 25wherein run-time of the rechargeable battery in the notebook computer isincreased by at least ten percent.
 27. An integrated circuit packagecomprising: a heat transfer device having an integrated circuit matingsurface; a compressor coupled to the heat transfer device; and anelectricity generating device coupled to the compressor.
 28. Theintegrated circuit package of claim 27 further comprising a coolingdevice coupled to the electricity generating device and to the heattransfer device, the cooling device configured to cool excess vapor fromthe electricity generating device for use again in the heat transferdevice.
 29. The integrated circuit package of claim 28 wherein thecooling device is a thermoelectric cooler or a condenser.
 30. Theintegrated circuit package of claim 29 wherein the condenser is integralwith the heat generating device, further wherein the heat generatingdevice is a vapor chamber heat sink.
 31. The integrated circuit packageof claim 30 further comprising a fan thermally coupled to the vaporchamber heat sink.
 32. The integrated circuit package of claim 27further comprising an integrated circuit die thermally coupled to theintegrated circuit mating surface of the heat transfer device.
 33. Anotebook computer comprising: a rechargeable battery; and an electricalenergy-producing heat sink system coupled to the rechargeable battery.34. The notebook computer of claim 33 further wherein the electricalenergy producing heat sink system includes a generator electricallycoupled to the rechargeable battery.
 35. The notebook computer of claim34 wherein the run-time for the notebook computer is increased by atleast ten percent.
 36. A battery charger comprising: means fortransferring vapor from a heat source to a pressurizing device; meansfor converting pressurized vapor from the pressurizing device tomechanical energy; means for converting mechanical energy to electricalenergy; and means for supplying current to a rechargeable battery havingterminals with the electrical energy.
 37. The battery charger of claim36 wherein the means for transferring vapor is a heat pipe orthermosyphon.
 38. The battery charger of claim 37 wherein the means forconverting pressurized vapor is a turbine.
 39. The battery charger ofclaim 38 wherein the means for converting mechanical energy is agenerator.
 40. The battery charger of claim 39 wherein the means forsupplying the current to the rechargeable battery comprises applicationof an electrical current to the terminals with the electrical energy.41. A battery charger comprising: a vapor-producing device adapted tointake heat from an integrated circuit package and expel vapor to avapor pressurizing device, the vapor pressurizing device thermallycoupled to the vapor producing device; a mechanical energy-producingdevice mechanically coupled to the vapor pressurizing device and to anelectrical energy-producing device; and a current supplying deviceelectrically connected to the electrical energy-producing device and toa battery.
 42. The battery charger of claim 41 wherein the vaporproducing device is a vapor chamber heat sink.
 43. The battery chargerof claim 41 further comprising a vapor reliquifying device.
 44. Thebattery charger of claim 41 wherein the current supplying device is anelectrical wire.
 45. A method for providing electrical energy to arechargeable energy storage device comprising: vaporizing a workingfluid in thermal contact with a heat generating device to produce vapor;pressurizing the vaporized fluid to produce pressurized vapor; forcingthe pressurized vapor through turbine blades to produce mechanicalenergy; and converting the mechanical energy to electrical energy. 46.The method of claim 45 further comprising routing the electrical energyto the rechargeable energy storage device.
 47. The method of claim 46further comprising reliquifying excess pressurized vapor.
 48. The methodof claim 45 wherein the energy storage device is located in anelectronic device.
 49. The method of claim 48 wherein the electronicdevice is a notebook computer.
 50. A method for extending run-time for abattery-operated notebook computer comprising: generating heat with amicroprocessor; transferring the heat through a heat sink tocontinuously produce electrical energy, the heat sink including acompressor and a turbine generator; and providing the electrical energyto a battery in the notebook computer to recharge the battery, whereinrun-time is extended for the notebook computer.
 51. The method of claim50 wherein run-time is extended by at least ten percent.
 52. The methodof claim 50 comprising continuously extending run-time while thebattery-operated notebook is turned on.